What are precious metals and base metals?

A piece of jewelry, if the jewelry jade is an actor, then the inlaid part is the script. There are no actors who are separated from the script. So what is jewelry? What is mosaic? In a broad sense, jewelry refers to all materials that can become jewelry and handicrafts after being polished and carved. It is a general term for natural jewelry, jade, and artificial gemstones. In the narrow sense, it refers to minerals, rocks, and organic materials produced in nature that are beautiful, durable, and rare, and can be carved and polished into jewelry and handicrafts. It is the mainstream product in the jewelry industry. The most important “precious metal” in inlay has stable chemical properties, abrasion resistance and firmness, and has a unique light color and texture. Whether it is made into jewellery alone or used as a basic inlay, it has good aesthetics. Metals include precious metals and base metals. The content of noble metal elements in the earth’s crust is very rare, among which gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), osmium (Os), ruthenium (Ru), etc. Eight species belong to precious metals. Except for other metals, they are classified as base metals. In the traditional sense, precious metals and precious gemstones have always been representatives of the rights, status, taste and wealth of the owner. With the renewal of society and the diversification of aesthetics, base metals have gradually emerged.

Precious metals

  • Gold: The earliest metal mined and used by mankind. Known as the “king of metal”. It is chemically stable and will not oxidize even if it burns in the air until it melts. (A method for testing pure gold), insoluble in strong acids (sulfuric acid, hydrochloric acid, nitric acid), but soluble in aqua regia and potassium cyanate solution. Natural pure gold is called natural gold in mineralogy, equiaxed crystal system, golden yellow, metallic luster, Mohs hardness 2.5, very good ductility, 1g of gold can be elongated into 3420m filaments. Density 19.32g/cm3 (the purity of gold can be checked by using a hydrometer)

The common “gold” in the market is mostly gold alloys that improve and obtain new properties. For example, increase the hardness to facilitate inlaying, and melt into other metals for rich colors. According to the gold content, it can be divided into: Thousands of pure gold, the percentage of gold content is not less than 999, and the imprint is marked as “thousand pure gold”, “gold 999”, “Au999” and “G999”. (GB11887-2012 “Regulations and Nomenclature of Jewelry Precious Metal Purity” Amendment No. 1, which will be implemented on May 4, 2016. Even gold jewelry with a purity of 999.0‰ can only be marked as “pure gold”, but not It’s called “Thousand Pure Gold”.)Pure gold, with a gold content of not less than 990 per thousand, and the imprints are “Pure Gold”, “Gold 990”, “Au990” and “G990”. The official solid gold seals on the market are marked with “full gold 999”. Thousands of pure gold is pure gold, but the pure gold is not necessarily one thousand pure gold, you must see the mark and certificate when purchasing. K gold. K is the international unit, and it is specified as 24k when the gold content is 1000 per thousand. The gold content of 1K gold is about 41.66‰. Common K gold is 22K (916‰), 18K (750‰), 14K (585‰), 9K (375‰), etc. The imprint is marked as “Auxxx”, “Gxxx”, “GxxK” and “Gold xxx”. The “color gold” that ever Phenibut Suppliers yone often refers to also belongs to K gold, which is the color formed by melting other metal elements into the gold matrix. The correct name for the color karat gold, such as yellow karat gold (yellow karat gold, karat yellow), white karat gold (white karat gold, karat white. It needs to be distinguished from 18k white gold, platinum generally refers to platinum), red karat gold ( Red k gold, k red)…Gold-plated, gold products production process. Arrange extremely fine pure gold wire (about 0.3mm in diameter) or gold particles on the surface of the model, and weld it at a high temperature of 1000°C. The gold content of the gold-plated layer is not less than 585 per thousand, the thickness of the covering layer (plating layer) is not less than 0.5μm, and the thin-layer gold-plated layer is greater than or equal to 0.05μm and less than 0.5μm. The mark “P-Au”, thin gold plating is not allowed to print marks. Gold-clad, an ancient craft, presses a layer of gold foil on a copper sheet. The gold content of the covering layer is not less than 375‰, and the thickness is not less than 0.5μm. The imprint “L-Au”

  • Silver: It was discovered and used by China 4000 years ago, and it is also the most widely used precious metal today. In a period of history, silver was twice as expensive as gold. Silver mainly exists in nature as elemental silver and is produced as a compound. Metallic luster, silver white, Mohs hardness 2.7, good conductivity. With good ductility, 1g of silver can be elongated into filaments of 1800-2000m. The chemical properties are relatively stable. It does not oxidize at room temperature, but has poor corrosion resistance. It will react with sulfur-containing substances or gases containing sulfur dioxide and hydrogen sulfide in humid air to produce black silver sulfide. Silver compounds are also very sensitive and react with arsenic (arsenic) and halogen elements to produce black silver arsenide and halide. It does not react with dilute nitric acid and dilute hydrochloric acid, but can quickly react with nitric acid to produce silver nitrate.

The types of silver are more complicated. In 1995, the People’s Bank of China stipulated that all silver refined by the smelter designated by the People’s Bank of China should be finished silver, and the rest should be variegated silver regardless of fineness. According to the national standard, it is divided into Thousands of pure silver: The silver content is not less than 999 per thousand, and the imprint is “thousand pure silver”. Pure silver: The silver content per thousand is not less than 990, and the imprint is “Pure silver”. 925 silver: The silver content per thousand is not less than 925, and it is marked with “925 silver”, “S925” and “Ag925”. 800 silver: The silver content per thousand is not less than 800, and the imprint is “800 silver”, “S800” and “Ag800”. The highest purity of silver and its silver alloy jewelry is 999. Those with a purity higher than 999‰ can only be called thousand pure silver; those with a minimum of 800 and less than 800‰ cannot be called silver jewelry. Silver plating: The process is similar to gold plating, the thickness of the covering layer is not less than 2μm, the silver content is not less than 925‰, and the imprint is “PnAg”. Silver-clad: similarly gold-plated, the thickness of the covering layer is not less than 2μm, the s Phenibut Suppliers ilver content is not less than 925‰, and the imprint is “LnAg”. Miao silver: The unique silver of the Miao nationality is an alloy of silver, cupronickel (a name for copper-nickel alloy) and nickel. The silver content is usually 20% to 60%. The main ingredient is copper. Tibetan silver: Traditionally it is 30% silver + 70% copper, and a small amount of silver is mixed with white copper. There is a kind of Tibetan silver that does not contain silver and is copper-nickel alloy. Taiyin: also called black silver. Jewelry that has been specially distressed by taking advantage of the blackening properties of silver when it meets sulfur. Low platinum silver: an alloy of silver and a small amount of platinum (rhodium, iridium).

  • The platinum group includes platinum (tin white), palladium (steel white), osmium (blue and white), ruthenium (blue and white), rhodium (silver white), and iridium (white) element. The platinum group has a high melting point and is a refractory metal. It has high chemical stability to acids, especially osmium, ruthenium, rhodium and iridium, not only insoluble in strong acids, but even in aqua regia. (Only platinum and palladium are soluble in aqua regia)

Palladium is an active member of the platinum family. It is soluble in aqua regia, as well as concentrated nitric acid and hot sulfuric acid. In the current market, only platinum and palladium in the platinum group can be used as jewelry. 1. Platinum, heavy metal, high density, low hardness, good electrical conductivity, thermal conductivity, and ductility. Platinum per thousand feet: the platinum content per thousand is not less than 999‰, and the mark is “Platinum per thousand feet” and “pt999″Platinum per thousand is not less than 990‰, and the mark is “full Platinum” “pt990″950 platinum: not less than 950‰, imprint “pt950″900 platinum: not less than 900‰, imprint “pt900″850 platinum: no less than 850‰, with the mark “pt850″2. Palladium, a precious metal for jewelry newly developed in recent years, is similar to platinum, but the price is relatively cheap. Stable at room temperature, does not react with phosphoric acid, acetic acid, hydrofluoric acid, perchloric acid, etc.; reacts slightly with hydrochloric acid, sulfuric acid, and hydrobromic acid; quickly reacts and corrodes with nitric acid, ferric chloride, hypochlorite, and wet halogen . Thousand-foot palladium: the palladium content per thousand is not less than 999‰, and the mark is “thousand-foot palladium” and “Pd999″The full palladium: not less than 990‰, and the mark is “full palladium” “Pd990″950 Palladium: not less than 950‰, imprint “Pd950″500 Palladium: not less than 500‰, imprint “Pd500” Color palladium: Palladium and enamel are made by a special process.

Base metals

The main metals used as jewelry are copper, zinc, aluminum, titanium, iron, tungsten, rare earths, etc., among which nickel, lead, mercury, Cadmium, arsenic, and hexavalent chromium are harmful elements to the human body.

  • Copper

It is divided into pure copper and copper alloy. Pure copper is often used as a simulation necklace; copper alloy is an alloy in which copper is the base and other elements are added. (Brass: copper-zinc binary alloy, yellow. Adding rare earth elements can be refined into nearly 18k~22k gold, used to imitate gold jewelry. Cupronickel: divided into simple cupronick Phenibut powder wholesale el, complex cupronickel, industrial White copper. The hardness and gloss are close to silver. Bronze: red copper, tin, lead and other alloys. Three-color copper: red copper, cupronickel, brass three different colors of copper alloy materials)

  • Titanium and titanium alloys

Titanium is the only metal that has no effect on human autonomic nerves and taste nerves. It is medically called “biophilic metal”. It is more popular in the world, and there are very few produced in China.

  • Stainless steel

In the atmosphere, water, acid, alkali, salt and other solvents or corrosive media, the general term for steel with certain chemical stability. The good corrosion resistance is due to the addition of chromium, as well as Ni, Mn, V, W, B, etc. Because ni is harmful, manganese is used instead.

  • Tungsten gold (tungsten steel)

The appearance is similar to steel, with high hardness, non-wear, non-fading properties, and very stable chemical properties.

  • Hazardous elements

According to the national standard, no harmful elements should be added to precious metals (including base metals). 1, nickel may cause skin irritation. Our country stipulates that whether it is used in precious metals, base metals and their synthetic jewelry, the release amount is less than 0.5μg (cm3·week) for body parts perforated products. 2. Lead is the killer of beauty, I understand that it may be in ancient cosmetics, in order to pursue the whiteness of the skin, the so-called exhausting the lead. In fact, it is a more polluting metal. Overdose can affect the central nervous system, damage the kidneys and immune system. Lead compounds can also cause cancer. It is not only harmful to the human body, but also to the environment. Once it enters the ecological environment, it is difficult to degrade and has strong potential toxicity. It is a strong pollutant. It is generally used in base metals and artificial jewelry. If it is not deliberately added, precious metals are not included. 3. Cadmium can cause muscle atrophy, cause pathological fractures, etc., the pain is unbearable and unable to sleep. Mainly used in the solder of metal jewelry and base metal jewelry. If it is not deliberately added, no precious metals are included. 4. Arsenic can be used for medical treatment and is toxic. Depends on chemical form and concentration. Low-concentration pentavalent arsenic is non-toxic, while trivalent arsenic is highly toxic. Moreover, the toxicity of arsenic is cumulative, and mammals have a certain tolerance to arsenic, and the onset of arsenic often occurs after several years of poisoning. Damages mainly occur in the digestive system, nervous system, and cardiovascular system. 5. Chromium has different toxicity in its immobility state. Metal chromium is inactive and harmless. Hexavalent chromium is more toxic than trivalent chromium and is absorbed through the mouth, skin, and respiratory tract. In fact, chromium is also very important (toxicity mainly comes from hexavalent chromium). Chromium is an essential element for insulin to participate in the process of sugar metabolism. Severe chromium deficiency can also affect healthy development. Be careful when choosing metal jewelry. Generally speaking, noble metals are not deliberately added harmful metals, and usually do not contain harmful elements. Not every base metal is added, such as copper and copper alloys, and titanium metals are all good choices. As long as the production factory strictly follows the national standard, it generally has no effect on the human body, and you can buy and wear it with confidence.